The fiery South Carolina conservative, who established the Senate Tea Party Caucus, provides a dramatic stylistic shift from Edwin Feulner, the quiet 71-year-old president and founder he will replace.

“It’s just like having a think tank run by me and then handing it off to Ben Affleck. You know, all of a sudden it has a real profile,” said Jeffrey Taylor, a Republican lobbyist at U.S. Government Relations International.

The move publicly solidifies the think tank’s gradual move further rightward. Heritage established an advocacy arm in 2010 in an effort to capitalize on tea party enthusiasm and has since become an increasingly prominent player in the national political debate, weighing in on most major legislative issues.

Heritage Action, organized under tax code 501(c)(4) as a tax-exempt social welfare organization, has been particularly vocal in its efforts to repeal President Barack Obama’s health care law and in its opposition to any and all international agreements, including the United Nations treaty on the rights of the disabled, which the Senate rejected this week. The nonprofit raised more than $3 million in its first year of operation, its tax returns show, and it used some of that money to run advertisements pressuring Republicans to sign a measure to repeal the health care law.

Wonkish Washington think tanks have become increasingly action-oriented in recent years, favoring the mold of the Democratic Center for American Progress over a more passive policy tack. A conflict over the control of the libertarian Cato Institute earlier this year centered around this very question.

DeMint told the Wall Street Journal he did not intend to politicize The Heritage Foundation, but some Republican lobbyists worried that the senator, known for bucking Republican leadership on Capitol Hill, could be just as disruptive to the Republican Party in his new role outside of Congress.

“I’m hoping they broaden the conservative horizon and become the catalyst for developing new ideas based on the principles below, rather than attack Republicans for being insufficiently conservative,” said Jack Howard, vice chairman of Wexler Walker Public Policy Associates. “They need to focus on making it easier for people to embrace the conservative agenda rather than harder.”

Taylor said he did not expect such a shift, but warned of the risks to the well-funded organization.

“I think if Heritage moves in a dramatically more activist role, it might lose some of the supporters,” he said.

The think tank raised just less than $74 million in 2011, only 4 percent of which came from corporations, according to its most recent annual report. Unlike some other think tanks, Heritage does not do contract work for companies, Heritage Vice President of Development John Fogarty told Roll Call last year.

Prominent conservative activist Paul Weyrich and Joseph Coors, president of Coors Brewing Co., both now deceased, helped Feulner found Heritage in 1973. Throughout the 1980s, it remained small, focusing primarily on tax and trade issues. When President Bill Clinton took office, it became an outpost for displaced Republicans and started to attract larger donations.

Feulner had been planning to step down for more than a year. He will be named chancellor of Heritage, a new position, and will continue in a part-time capacity as chairman of the foundation’s Asian Studies Center.